1. Field of the Invention
The invention relates to an irradiation device for irradiating objects, in particular with ultraviolet and/or infrared and/or visible electromagnetic radiation, comprising a housing which comprises an outlet aperture for electromagnetic radiation, which outlet aperture is aligned to the object to be irradiated, as well as comprising at least one elongated radiation source, arranged in the housing, for electromagnetic radiation. Furthermore, the invention relates to an operating system for a radiation source according to the invention.
2. Description of the Related Art
Irradiation devices, in particular for UV light, are used for photochemically influencing irradiated objects. Important applications include the curing of printing inks, adhesives and coatings, as well as sterilization and medical irradiation. In particular for applications in the context of wooden board materials and floor coverings, UV irradiation devices with very high radiation outputs are used, with the irradiation width ranging up to several meters.
In UV irradiation devices, above all gas discharge lamps are used as radiation sources, in which gas discharge lamps a plasma is generated by the vaporization of metals. The lamps essentially comprise a tubular glass body, two electrodes, two foil fuse-ins as well as two lamp bases. Depending on the lamp type, the operating temperatures at the glass body can reach between 700° C. and 900° C.
All known elongated UV irradiation devices comprise a radiation source, suspended at both ends, which radiation source can be partly enveloped by a reflector.
The radiation sources are designed such that the energy absorbed by the glass is released by free convection and by radiation. An equilibrium between the absorbed energy quantity and the released energy quantity would occur at a temperature of the glass body of approx. 800° C. However, in practical application, the reflectors and the housing of the UV irradiation device impede this state. Reflection of heat radiation, and at times heat accumulation, can occur near the radiation source.
In order to overcome this problem, attempts have been made to set the temperature of the radiation source within the optimal operating range by means of improved air cooling systems. However, such arrangements are associated with a disadvantage that even with optimal cooling of the freely suspended irradiation source, i.e. an irradiation source which is only held by its end, beyond a critical electrical energy level in combination with a critical design length, the temperature of the glass body is such that all known radiation sources suffer deformation as a result of gravitational forces. Such sagging is evident in all irradiation sources, not just in UV radiation sources. Due to creep action in the glass body, whose operating temperature is just slightly below the temperature where material assumes a plastic state, all such radiation sources sooner or later suffer deformation. This particularity is already taken into account when the housing shape and the distance to the object to be irradiated are designed. However, if the deformation becomes excessive, then the plasma arising in the lamp can establish contact with the glass at a point. Such contact causes overheating and consequent destruction of the glass body of the radiation source.
In order to reduce deformation it is thus necessary according to the state of the art to reduce the design length of irradiation devices, in particular of UV irradiation devices, and at the same time to reduce the electrical output in the case of longer design lengths. According to the state of the art, large irradiation widths require several irradiation devices to be arranged side by side.